For practical application of wireless power transfer, research and development that reduces power loss in the entire system has been actively carried out in recent years. Particularly in systems where a power transmitting resonance mechanism and a power receiving resonance mechanism form an electromagnetic resonance field to wirelessly transfer power using electromagnetic field resonance coupling, it is possible to simplify the process of power transfer and reduce power loss, unlike in systems where a high-frequency magnetic field is applied to a resonator (see International Publication No. 2012/101905).